When a semiconductor circuit is manufactured it is necessary to form a plurality of via cavities between individual layers of the semiconductor circuit in order to provide conduits for electrical communication between metal layers of the semiconductor circuit. In order to facilitate the efficient filling of the via cavities with metal fill material (e.g., aluminum) the sidewalls of the via cavities should have an appropriately shaped profile. That is, the shape of a via cavity should not interfere with a subsequent via fill process.
Prior art methods of forming a via cavity, however, often leave one or more sharp edges in the sidewall profile of the via cavity. Other prior art methods of forming a via cavity create via cavity sidewalls that have a concave profile. The presence of sharp edges or the presence of a concave profile in a via cavity sidewall tends to catch portions of the fill material and cause the fill process of via cavity to be incomplete. That is, voids in the fill material may be caused by the sharp edges in the sidewalls of the via cavity. Voids in the fill material may also be caused by the presence of a concave profile in the sidewalls of the via cavity.
Therefore, there is a need in the art for a system and method that is capable of providing a via cavity in a semiconductor circuit that has an optimally shaped sidewall profile. There is also a need in the art for a system and method that is capable of providing a via cavity having a sidewall profile that facilitates a subsequent via fill process.